simplify graph signal handler

src/daemons/GraphDaemon.cpp

@@ -9,6 +9,9 @@
 #include <string.h>
 #include <thrift/lib/cpp2/server/ThriftServer.h>
 
+#include <mutex>
+#include <thread>
+
 #include "common/base/Base.h"
 #include "common/base/SignalHandler.h"
 #include "common/fs/FileUtils.h"
@@ -43,6 +46,11 @@ extern Status setupBreakpad();
 DECLARE_string(flagfile);
 DECLARE_bool(containerized);
 
+enum ServiceStatus { STATUS_UNINITIALIZED = 0, STATUS_RUNNING = 1, STATUS_STOPPED = 2 };
+std::atomic<ServiceStatus> serverStatus_{STATUS_UNINITIALIZED};
+std::mutex muStop_;
+std::condition_variable cvStop_;
+
 int main(int argc, char *argv[]) {
   google::SetVersionString(nebula::versionString());
   if (argc == 1) {
@@ -166,33 +174,56 @@ int main(int argc, char *argv[]) {
     return EXIT_FAILURE;
   }
 
-  gServer->setPort(localhost.port);
-  gServer->setInterface(std::move(interface));
-  gServer->setReusePort(FLAGS_reuse_port);
-  gServer->setIdleTimeout(std::chrono::seconds(FLAGS_client_idle_timeout_secs));
-  gServer->setNumAcceptThreads(FLAGS_num_accept_threads);
-  gServer->setListenBacklog(FLAGS_listen_backlog);
-  if (FLAGS_enable_ssl || FLAGS_enable_graph_ssl) {
-    gServer->setSSLConfig(nebula::sslContextConfig());
-  }
-  setupThreadManager();
-
   // Setup the signal handlers
   status = setupSignalHandler();
   if (!status.ok()) {
     LOG(ERROR) << status;
     return EXIT_FAILURE;
   }
 
-  FLOG_INFO("Starting nebula-graphd on %s:%d\n", localhost.host.c_str(), localhost.port);
-  try {
-    gServer->serve();  // Blocking wait until shut down via gServer->stop()
-  } catch (const std::exception &e) {
-    FLOG_ERROR("Exception thrown while starting the RPC server: %s", e.what());
+  std::thread graph_thread([&] {
+    gServer->setPort(localhost.port);
+    gServer->setInterface(std::move(interface));
+    gServer->setReusePort(FLAGS_reuse_port);
+    gServer->setIdleTimeout(std::chrono::seconds(FLAGS_client_idle_timeout_secs));
+    gServer->setNumAcceptThreads(FLAGS_num_accept_threads);
+    gServer->setListenBacklog(FLAGS_listen_backlog);
+    if (FLAGS_enable_ssl || FLAGS_enable_graph_ssl) {
+      gServer->setSSLConfig(nebula::sslContextConfig());
+    }
+    setupThreadManager();
+    serverStatus_.store(STATUS_RUNNING);
+    FLOG_INFO("Starting nebula-graphd on %s:%d\n", localhost.host.c_str(), localhost.port);
+    try {
+      gServer->serve();  // Blocking wait until shut down via gServer->stop()
+    } catch (const std::exception &e) {
+      FLOG_ERROR("Exception thrown while starting the RPC server: %s", e.what());
+      return;
+    }
+    serverStatus_.store(STATUS_STOPPED);
+    FLOG_INFO("nebula-graphd on %s:%d has been stopped", localhost.host.c_str(), localhost.port);
+  });
+
+  while (serverStatus_ == STATUS_UNINITIALIZED) {
+    std::this_thread::sleep_for(std::chrono::microseconds(100));
+  }
+
+  if (serverStatus_ != STATUS_RUNNING) {
+    LOG(ERROR) << "Graphd server start failed";
+    gServer->stop();
     return EXIT_FAILURE;
   }
 
-  FLOG_INFO("nebula-graphd on %s:%d has been stopped", localhost.host.c_str(), localhost.port);
+  {
+    std::unique_lock<std::mutex> lkStop(muStop_);
+    while (serverStatus_ == STATUS_RUNNING) {
+      cvStop_.wait(lkStop);
+    }
+  }
+
+  gServer->stop();
+
+  graph_thread.join();
 
   return EXIT_SUCCESS;
 }
@@ -208,7 +239,13 @@ void signalHandler(int sig) {
     case SIGINT:
     case SIGTERM:
       FLOG_INFO("Signal %d(%s) received, stopping this server", sig, ::strsignal(sig));
-      gServer->stop();
+      {
+        std::unique_lock<std::mutex> lkStop(muStop_);
+        if (serverStatus_ == STATUS_RUNNING) {
+          serverStatus_ = STATUS_STOPPED;
+          cvStop_.notify_one();
+        }
+      }
       break;
     default:
       FLOG_ERROR("Signal %d(%s) received but ignored", sig, ::strsignal(sig));